Any file (drawing or not) that is associated with a project, especially any file that would benefit from version control, should be stored in the project. Temporary files, such as preliminary design drawings, do not need to be stored in the project.
For ease of use, all projects should use consistent folder structure and folder names. A practical structure is provided when you use the project template. You can easily create your own custom template if the default version is not suitable.
You do not need to create a folder for point database files or survey database. These are automatically stored directly beneath the main project folder.
A project can also include files that are not drawings. Using Vault, create folders for such files directly under the project folder. Possible folder names might include: Proposals, Client Correspondence, and Contracts. You can store and access the files in non-drawing folders using the Vault tool.
When you work on objects, you check associated drawings out of a vault and work with them from working folders. The objects in a working folder are physically copied from a Vault file store. Other users can still get read-only copies of the files, but they cannot edit them until you have checked them back in. In this way, you maintain a single master version of each drawing.
When you check a file back into a vault, the revised version from your working folder is copied to the file store on the server. The Vault database marks the file with the appropriate revision data and makes it available to other users.
You can change your working folder without risk to the data in the Vault database, but you typically change the working folder only if you need to work with projects in different Vault databases. To avoid confusion, use a separate working folder for each Vault database.
The default working folder location is C:\Civil 3D Projects.
Projects can be created at any level in the hierarchy below the working folder. For example, within the working folder, you could have a folder named for the year, and then you can store projects associated with that year inside that folder.
Autodesk Vault allows for projects and folders to be nested in any way, with as many levels as you want. When working with AutoCAD Civil 3D, projects are always added to the working folder. Within the working folder, projects can be created at any level in the hierarchy below the working folder (projects can be created directly within the working folder, or within a subfolder in the working folder). The Prospector tree can display project objects that exist in subfolders within the object type folders.
For best results, avoid creating a project inside another project. The Prospector tab in AutoCAD Civil 3D may display projects nested within other projects in an unexpected way. For example, folders that are empty may show up at different levels in Prospector than folders which are located at same level in the hierarchy as the empty folders, but which contain projects.
For more information on best practices with working folders, see Working Folder Configurations in the AutoCAD Civil 3D Best Practices guide.